Liquid pressure operated motor



Sept. Z7, 1966 M. 'rl-:RHC

LIQUID PRESSURE OPERATED MOTOR Filed Oct. '7, 1965 INVENTOR.

Mlm/a Zw//a BY//MWL j ill United States Patent 3,274,896 LIQUID PRESSURE OPERATED MOTOR Mikko Terho, Naantali, Finland Autolava Oy, Raisin, Finland) Filed Oct. 7, 1963, Ser. No. 315,427 2 Claims. (Cl. 91-198) 'Ilhis is a continuation-in-part of patent application Serial 'No. `31,366, tiled May 24, 1960, now abandoned, and entitled Liquid Pressure Operated Motor.

The invention presented herein deals with a device in which the reciprocating motion of pistons is accomplished by the application under pressure of the liquid used in motor cars, tractors, or ithe like, which motion then is transformed into rotational motion without requiring a connecting rod `and crank shaft, `and which rotary motion can be utilized in the lift devices of ymotor cars and tractors, wire Winches, tipping devices, and similar equipment.

The invention is illustrated by the accompanying drawings, wherein:

FIGURE 1 presents in detail a cross section of the liquid pressure motor, and

FIGURES 2, 3 and 4 schematically show some of the `details of the device according to the invention.

The ydevice comprises la shaft 1 to which a cylinder block 2 is secured by means of a key 3. Block 2 is provided with cylinders 4a, 4b arranged circularly around shaft 1, e.g., in the case presented by FIGUR-E l, four cylinders at equal distances from each other. rIlhe cylinders are provided with pistons 5a, 5b, of which 5a is cut away in such a Way in the figure that spring 6a is completely visible. Spring y6a 1and 6b urge the pistons away from the cylinders, so that balls 7a, 7b engaged in the extreme ends of the pistons in Ia mobile fashion relative to the pistons are rurged against the so-called crown 8, forming a closed ring around shaft 1. The term crown derivatives Ifrom the fact that one end edge '9 of this ring-shaped 4block 8 is smooth, while the opposite end edge 10 is provided with elevations and curved valleylike depressions in between.- lIn the case presented by FIGURE 1l there are three of these elevations on the crown, Iand -between them correspondingly, three depressions. Crown 8 is vrigidly fixed at its edge 9 to journal block 11, which in turn is 'firmly connected by means of support 12 to the chassis of a motor car, or the like.

However, shaft 1 is able to rotate in block 11 and this is aided, e.g., by bearing seal 13. Cover 14 is fastened and sealed to block 11 by means of seal 15. Similarly, the other end of cylinder-shaped cover 14 is joined by means of liquid-tight seals '16 to the other 'journal block 17, within which shaft li can rotate aided by bearing seal 18. Thanks to the seals and the outer cover, the device can be suitably kept partly filled with oil.

For example, when channel 20a communicates with the fluid under pressure, fluid will force its Way through the channels into cylinder 4a in the direction indicated by the arrow. Here the pressure fluid forces piston Sa out from cylinder 4a, whereupon ball 7a begins to move along the sloping edge portion 10a of crown 8 away from cylinder block 2, giv-ing at the same time a cylinder lblock 2, including shaft 1 fixed relative thereto, a rotational motion. Piston 5b will move in a corresponding manner in its cylinder as ball 7b `glides Ialong inclined edge portion l10b of crown 8 towards cylinder block 2. Correspondingly, spring 6b is compressed, permitting the fluid in cylinder 4b to flow into channel 38!) in the direction indicated by arrow 2lb, and to discharge therefrom.

When piston 5a has reached its extereme position, i.e., ball 7a has rolled along the incl-ined edge portion to the bottom of the lobe of crown 8, or close to this point,

ICC

pressure iluid in channel 20a is kept from entering cylinder 4a in a direction of arrow 21a, and instead the cylinder will communicate with channel 38a, through which the fluid is able to discharge `from cylinder 4a. Before piston 5a reaches its extreme position, or it dead point, one or several of the other piston-s meanwhile begin moving in their respective cylinders away from their extreme positions las the balls at the ends of the pistons start rolling along the inclined edge portions of the crown away from the cylinder block, and `at the same time the channels communicating with t-hese cylinders open so that the entering pressure fluid pushes the pistons away from the cylinders. Therefore, the crown may have, for instance, three high and three low points, even if there are four pistons. The cylinder block may also, due to inertia, force the balls to pass the high and low points. In this way the operation of the device continues. There are always one or several pistons moving out lfrom the cylinders while fluid under pressure is flowing in, at the same time as liquid is leaving those cylinders in which the pistons are moving inwards. Cylinder block 2 with shaft 1 fixed to it rotates in this manner in the direction of arrow 22, or clockwise as seen from the left in FIG URE l.

FIGURIE 3 gives a schematic presentation of the fluid distribution passages 23, 24 located in block 17. These passages alternately communicated with the fluid under pressure and with the outlet channels conveying pressure fluid from the motor. Passages 23, 24 are located relative to each other in such a way that each time one of the pistons is about to glide away from the cylinder block, the corresponding cylinder communicates with one of the passages 23 supplying pressure fluid, whereas those cylinders in which the piston is pushing fluid away communicate with passages 24, which perm-its fluid t-o leave. Thus, the number of passages 23 supplying pressure fluid should equal the number of ascending sides on the crown and are located at corresponding points, i.e., the points at which the piston Will move towards the crown; also, the number of passages leading duid away is equal to the number of descending sides on the crown land these passages are located at corresponding points, i.e., the point at which the piston will move towards the cylinder block. Figure 3 is only schematic, and yactually the outlet and inlet channels of the mechanism, according to FIGURE 1, yare not in the same plane, as FIGURE 3 appears to indicate.

In FIGURE 2 a small portionof the crown is illustrated as being straightened out to form a plane, and showing piston 5a, including its ball, gliding downhill in the direction of arrow 22, whereas piston 5b is ascending uphill.

However, the distribution of the pressure fluid into the cylinders, and the removal of the fluid from the cylinders present certain difficulties. Thus, if the passages in FIG- URE 3 are in reality located exactly as shown, the situation arises that the uid under pressure might get closed olf at a time a little before the farthest position of the corresponding piston, i.e., a little before the ball at the end of the piston would have reached the valley of the crown, and correspondingly, the ball at the low point might start to :ascend uphill and the piston at the same time start to press into the corresponding cylinder before this cylinder would communicate with outlet passage 24 of the fluid. It need not be said that this would lead to great difficulties, and eventually to the destruction of the mechanism. The fluid under pressure, being substantia-ily incompressible, would crack the cylinder under the compression in the cylinder if it had no way to leave, or the mechanism would not function in the rst place.

The danger of cracking referred to is still greater if (D the sealing engagement between the pistons and the corresponding cylinders is very tight.

Again, if supply and outlet passages 23, 24 we-re so close to each other that they would lie adjacent to each other, as they should theoretically, so that uid would be able to leave the cylinder immediately when the fluid under pressure has ceased pushing the piston and its motion has ceased, then this adjacent position of outlet and inlet passages 23 and 24 would result in mixing the fluid under pressure and the fluid leaving the cylinder in passages 23 and 24, i.e., the pressure would be equalized in passages 23 and 24 before it had time to affect the cylinders. Naturally, passages 23 'and 24 could be placed in such a way that they would not be adjacent, and still have the outlet channel of the liquid from the cylinder open at the sa-me instant as that when the entrance of uid under pressure into the same cylinder stops, but this would require eX- tremely accurate work in connection with the manufacture of the mechanism, yas well as in mounting, and despite this the mechanism would wea-r or otherwise be damaged, so that the original precision would not hold .true any longer.

It is much simpler to avoid the above-mentioned diiculties by providing the crown at its highest points with small plane surfaces, and similarly, the bottoms of the valleys. In order to make the matter clearer, FIGURE 4 gives schematically a view, to an overemphasized scale, of such a planar section at the top of crown 8, located between points 25 and 26, and at the bottom of the valley between points 34, 35. The circular surfaces of the crown are here imagined as straightened out to a plane. When cylinder block 29, lincluding its cylinders 27 and pistons 28, moves in the direction of arrow 30, to begin with ball 31 arrives at point 25 from the left, according to FIGURE 4, at which cylinder 27 still has to communicate with the outlet channels of the fluid, so that Huid Will be able to flow out from the cylinder While the piston is moving into the cylinder. The outlet opening of the uid cannot close before point 25 at the earliest, but it can close just as well also a little later, i.e., when ball 31 has, for instance, reached point 32. No damage will result thereby, although the pressure outlet opening is opened a little longer than necessary, because roller 31 is now moving along a plane surface, while correspondingly, piston 28 does not move in its cylinder. In this way a suitable interval may be left between closing of the outlet opening of the cylinder and the instant the piston stops moving, i.e., point 32 does not have to coincide with point 25, which greatly :aids the fabrication by reducing the amount of precision required. On the other hand, opening of the compression side of the cylinder may also occur a little before' ball 31 glides downhill, or while it still is moving along the plane surface between points 25 and 26. Thus, cylinder 27 may be Imade to communicate with the inlet channels of the pressure fluid before roller 31 is at point 26, for instance, when it is at point 33. This correspondingly reduces the need for precision work in manufacture, and no damage will result from making the cylinder communicate with the pressure fluid when the roller -still is moving along the planar surface, and while the piston is still stationary in the cylinder. Correspondingly, the pressure fluid supply opening, on arrival of ball 31 at plane 34, 35, may close a little after the roller has started to glide .along planar surface 34, 35, i.e., when the roller is atl point 36. Correspondingly, the outlet opening may open at point 37, i.e., a little before the piston begins t-o push fluid under pressure out from the cylinder.

In actuality these planar points (25, 26 and 34, 35) do not have to be of considerable length. They may be suitably, for instance, 8-10 mm. at the top of the crown and at the bottom. Also, the edges of the planar sections may be rounded off, so that the noller 31 is able to glide more easily from the sloping glide surfaces of the crown to the planar portions thereof, or away from said planar portions.

The fluid pressure-driven motor according to the present invention is applicable for tipping the platform of a truck, for hauling logs, or the like, eg., a detachable cargo platform may be disengaged from or replaced on the body of a truck, employing said motor as the power source. The motor has a relatively low r.p.m., avoiding the necessity of using a speed-reducing transmission, the speed of the motor being of the order of l0 revolutions per minute and being variable between 2 and 50 revolutions per minute,

While it would appear that there will be conditions where none of the pistons, including the balls on their ends, will be in engagement with sloping crown edge portions (dead points), the inertia of the cylinder block and parts carried thereby is substantial, so that it loperates as a flywheel and maintains itself in rotation through the dead point conditions. A separate iiywheel may also be used in addition, if necessary.

One purpose of springs 6a and 6b shown in FIGURE 1 is to keep the pistons, and correspondingly the balls, in their outermost positions in relation to crown 8, and correspondingly to maintain the balls always in contact with the crown edge. This is necesary when no pressure fluid is introduced into the mechanism and it is allowed to run empty, for instance, when lowering pieces of goods from a truck, which pieces have previously been lifted by means of wires from the rollers operated by the mechanism concerned. When an outside force causes shaft 1 and correspondingly, the cylinder block, to rotate, the pistons nevertheless move back and forth in the cylinders due to the yielding action of the springs, and at this time the pistons are pumping fluid into and out of the cylinders, but in a direction opposite to that when pressure fluid is being forced into the cylinders. The purpose'of causing iluid to circulate through the mechanism is to 'retard and to brake down the speed of rotation, so that the mechanism will permit slowly lowering goods, for instance, by means of rollers and wires from the platform of a truck to the ground.

It will be further seen that the coiled springs 6a and 6b bear between the pistons 5a :and 5b and the end wall of the cylinder block 2 and urge the cylinder block into sealing and bearing relation with the flattened inner surface of the housing end wall 17. The springs 6a and 6b thus serve a double function, namely, to urge the balls 7a and 7b into camming engagement with the crown edge portions, and also to provide the required sealing action between block 2 and end wall 17 to insure ecient and economical utilization of the pressure liquid.

The flow yof fluid through the mechanism may be regulated also by suitable variation of the cross-section of the ow channels, e.g., by choking at some point, and correspondingly, the speed of rotation of the mechanism when running empty may be regulated.

The invention is not restricted only to the mode of performance described above and illustrated in the drawings, but it may be varied in a number of ways Within the scope of the patent claims.

What is claimed is:

1. A device in which reciprocating motion given a piston by a liquid under pressure is transformed into rotational motion comprising a housing having opposing parallel end walls, one of said end walls having an inner flat bearing surface, a shaft journalled in said end Walls perpendicular thereto and to said at bearing surface, a cylinder block keyed on 4said shaft in said housing and having an end wall in bearing contact with said bearing surface, said cylinder block being formed with a cylinder bore extending parallel to said shaft, a piston slidably mounted in said cylinder bore, said piston being formed at its end remote from said flat end wall surface with a recess containing a ball, a stationary crown mounted on the other end wall of the housing concentrically with said shaft and formed with inclined cam edges facing said piston along which the ball is movable responsive to force exerted on the ball by the piston, said crown being formed with flattened edges between adjacent pairs of inclined cam edges, said flattened edges being in at least two different planes perpendicular to the shaft axis, said flattened edges alternately comprising crest edges closest to the cylinder block and Valley edges farthest from said cylinder block, the inclined cam edges alternating in nclination so that the ball alternately moves along said inclined cam edges toward and away from said cylinder block and travels -on said flattened crest and valley edges between such movements to prevent rectilinear move* ment of the piston, a coiled spring disposed axially in said piston and bearing between `said piston and said end wall of the block, urging said block end wall into sealing and bearing contact with said flat bearing surface, urging the piston away from the cylinder block and maintaining the ball in contact with the crown edges at all times, the block end wall having a passage opening at said bearing surface and communicating with the adjacent end of the cylinder bore, said one housing end wall having inlet and outlet passages opening at said bearing surface at locations to at times respectively register with said block end wall passage, means to supply pressure liquid into the cylinder bore through said inlet passage and block end wall passage a short time before the bal-l `starts to Imove along an adjacent inclined cam edge in a direction away from the cylinder block, whereby to cause said ball to engage the inclined cam edge, said inclined cam edge exerting a reaction on the piston to rotate the shaft, said block end wall passage moving out of registry with said inlet passage to seal said inlet passage a short time after the ball has reached the next adjacent flattened valley edge, and means to register said block end wall passage with said outlet passage, whereby to exhaust said cylinder bore, a short time before the ball moves olf said flattened Valley edge and engages the next adjacent inclined cam edge.

2. The structure of claim 1, and wherein the corners between the attened crest and valley edges and the adjacent inclined cam edges are rounded off to avoid sharp angles in the path of motion of the ball when the ball passes from :a flattened crest or valley edge to an adjacent inclined carn edge, and vice versa.

References Cited by the Examiner UNITED STATES PATENTS 137,261 3 /1873 Taylor 91-205 459,735 9/1891 Benham 91-205 2,667,862 2/1954 Muller 91-199 2,792,814 5/1957 `Christophel 9l-198 3,084,513 4/1963 Casassa et al. 91-175 FOREIGN PATENTS 73,843 12/ 1915 Switzerland. 248,917 3/ 1948 Switzerland.

MARTIN P. SCHWADRON, Primary Examiner.

FRED E. ENGELTHALER, SAMUEL LEVINE,

Examiners.

EDGAR W. GEOGHEGAN, P. E. MASLOUSKY,

Assistant Examiners. 

1. A DEVICE IN WHICH RECIPROCATING MOTION GIVEN A PISTON BY A LIQUID UNDER PRESSURE IS TRANSFORMED INTO ROTATIONAL MOTION COMPRISING A HOUSING HAVING OPPOSING PARALLEL END WELLS, ON OF SAID END WALL HAVING AN INNER FLAT BEARING SURFACE, A SHAFT JOURNALLED IN SAID END WALLS PERPENDICULAR THERETO AND TO SAID FLAT BEARING SURFACE, A CYLINDER BLOCK KEYED ON SAID SHAFT IN SAID HOUSING AND HAVING AN END WALL IN BEARING CONTACT WITH SAID BEARING SURFACE, SAID CYLINDER BLOCK BEING FORMED WITH A CYLINDER BORE EXTENDING PARALLEL TO SAID SHAFT, A PISTON SLIDABLY MOUNTED IN SAID CYLINDER BORE, SAID PISTON BEING FORMED AT ITS ENDS REMOTE FROM SAID FLAT END WALL SURFACE WITH A RECESS CONTAINING A BALL, A STATIONARY CROWN MOUNTED ON THE OTHER END WALL OF THE HOUSING CONCENTRICALLY WITH SAID SHAFT AND FORMED WITH INCLINED CAM EDGES FACING SAID PISTON ALONG WHICH THE BALL IS MOVABLE RESPONSIVE TO FORCE EXERTED ON THE BALL BY THE PISTON, SAID CROWN BEING FORMED WITH FLATTENED EDGES BETWEEN ADJACENT PAIRS OF INCLINED CAM EDGES, SAID FLATTENED EDGES BEING IN AT LEAST TWO DIFFERENT PLANES PERPENDICULAR TO THE SHAFT AXIS, SAID FLATTENED EDGES ALTERNATELY COMPRISING CREST EDGES CLOSET TO THE CYLINDER BLOCK AND VALLEY EDGES FARTHEST FROM SAID CYLINDER BLOCK, THE INCLINED CAM EDGES ALTERNATING IN INCLINATION SO THAT THE BALL ALTERNATELY MOVES ALONG SAID INCLINED CAM EDGES TOWARD AND AWAY FROM SAID CYLINDER BLOCK AND TRAVELS ON SAID FLATTENED CREST AND VALLEY EDGES BETWEEN SUCH MOVEMENTS TO PREVENT RECTILINEAR MOVEMENT OF THE PISTON, A COILED SPRING DISPOSED AXIALLY IN SAID PISTON AND BEARING BETWEEN SAID PISTON AND SAID END WALL OF THE BLOCK, URGING SAID BLOCK END WALL INTO SEALING AND BEARING CONTACT WITH SAID FLAT BEARING SURFACE, URGING THE PISTON AWAY FROM THE CYLINDER BLOCK AND MAINTAINING THE BALL IN CONTACT WITH THE CROWN EDGES AT ALL TIMES, THE BLOCK END WALL HAVING A PASSAGE OPENING AT SAID BEARING SURFACE AND COMMUNICATING WITH THE ADAJCENT END OF THE CYLINDER BORE, SAID ONE HOUSING END WALL HAVING INLET AND OUTLET PASSAGES OPENING AT SAID BEARING SURFACE AT LOCATIONS TO AT TIMES RESPECTIVELY REGISTER WITH SAID BLOCK END WALL PASSAGE, MEANS TO SUPPLY PRESSURE LIQUID INTO THE CYLINDER BORE THROUGH SAID INLET PASSAGE AND BLOCK END WALL PASSAGE A SHORT TIME BEFORE THE BALL STARTS TO MOVE ALONG AN ADJACENT INCLINED CAM EDGE IN A DIRECTION AWAY FROM THE CYLINDER BLOCK, WEREBY TO CAUSE SAID BALL TO ENGAGE THE INCLINED CAM EDGES, SAID INCLINED CAM EDGE EXERTING A REACTION ON THE PISTON TO ROTATE THE SHAFT, SAID BLOCK END WALL PASSAGE MOVING OUT OF REGISTRY WITH SAID INLET PASSAGE TO SEAL SAID INLET PASSAGE A SHORT TIME AFTER THE BALL HAS REACHED THE NEXT ADJACENT FLATTENED VALLEY EDGE, AND MEANS TO REGISTER SAID BLOCK END WALL PASSAGE WITH SAID OUTLET PASSAGE, WHEREBY TO EXHAUST SAID CYHLINDER BORE, A SHORT TIME BEFORE THE BALL MOVES OFF SAID FLATTENED VALLEY EDGE AND ENGAGES THE NEXT ADJACENT INCLINED CAM EDGES. 